Chalcedony is a microcrystalline variety of quartz that forms in botryoidal, lamellar, or fibrous structures. It is usually translucent or opaque and can come in a wide range of colors, including white, blue, gray, pink, green, and brown. Some well-known types of chalcedony include agate, carnelian, onyx, and jasper. Chalcedony has a Mohs hardness of 6 to 7, making it durable enough for beads, cabochons, and ornamental carvings. It is found in volcanic rocks and sedimentary deposits and is commonly sourced from regions like Brazil, India, and the United States.